Geometry exam 2026

point

An exact location in space with no size.

line

A straight path that extends infinitely in both directions.

plane

A flat surface that extends infinitely in all directions.

distance formula

The square root of (x₂ − x₁)² + (y₂ − y₁)².

midpoint formula

((x₁ + x₂)/2, (y₁ + y₂)/2)

slope

Change in y over change in x (rise/run).

parallel lines

Lines that never intersect and have equal slopes.

perpendicular lines

Lines that intersect at 90° and have negative reciprocal slopes.

angle

A figure formed by two rays with a common endpoint.

complementary angles

Angles that add to 90°.

supplementary angles

Angles that add to 180°.

vertical angles

Opposite angles formed by intersecting lines; they are equal.

adjacent angles

Angles next to each other that share a side.

Triangle Sum Theorem

The sum of interior angles in a triangle is 180°.

isosceles triangle

A triangle with two equal sides and angles.

equilateral triangle

A triangle with all sides and angles equal (60° each).

scalene triangle

A triangle with no equal sides.

Pythagorean Theorem

a² + b² = c².

area of a triangle

(1/2) × base × height.

area of a rectangle

Length × width.

area of a circle

πr².

circumference of a circle

2πr

polygon

A closed figure made of straight line segments.

regular polygon

All sides and angles are equal.

interior angle sum formula

(n − 2) × 180.

congruent

Same size and shape.

similar

Same shape, different size (proportional sides).

corresponding angles

Angles in the same position when lines are cut by a transversal.

volume of a rectangular

Length × width × height.

volume of a cylinder

πr²h.

surface area

Total area of all faces of a 3D figure.

right angle

90°.

acute angle

Less than 90°.

obtuse angle

Greater than 90°.